Validated CFD-Based Performance Characterization and Cavitation-Susceptibility Screening for Comparative Turbine Selection in Micro-Hydropower Systems

Turbine selection requires information on the operating range as well as peak efficiency. This paper extends previously documented bench-scale Francis, Pelton, and Cross-flow turbine data through a new analysis of CFD and laboratory performance curves. The original ANSYS CFX (2025) calculations used steady incompressible RANS, standard k–ε closure, and Frozen-Rotor coupling. The reported global comparison gives relative-deviation ranges of 1.13–9.96% for shaft power and 0.83–4.67% for hydraulic efficiency; geometry adjustments against the same benchmarks prevent treating this comparison as independent validation. The present analysis extracts plotted operating points and normalizes power and efficiency by their sampled maxima and speed by the corresponding peak locations. Approximate upper limits for retaining 90% of the sampled maximum efficiency occur at normalized speeds of 1.13, 1.43, and 1.06 for the Francis, Pelton, and Cross-flow cases, respectively. These describe the recorded operating paths, which have different discharges and varying heads, rather than universal turbine-family characteristics. Static-pressure plots identify locations for further investigation, but their incomplete pressure reference prevents quantitative cavitation-margin or vapor-volume assessment. The resulting qualitative selection workflow connects operating-speed compatibility and performance retention to site-specific hydraulic, generator, manufacturing, and maintenance checks.